To provide insight into direct interspecies electron transfer (DIET) via carbon-based materials and ferric oxides, the effects of three conductive materials (i.e. activated carbon (AC), iron modified activated carbon (FEAC) and goethite (FEOOH)), on methanogenesis from volatile fatty acids (VFAs) were evaluated. Under the acid stress (~4 g/L VFAs), the maximum methane yield of 266 mL/g-chemical oxygen demand (COD) was found in the FEOOH supplemented reactor, which was 48% higher than that of AC reactor. The reasons for the enhanced activity of the electron transport chain and extracellular electron transfer ability by FEOOH include: 1) the activation on iron-containing enzymes that involved in methanogenesis and acidogenesis; 2) selective enrichment on functional microorganism. The higher electron donating capacities (EDC) value of FEOOH may be a triggering factor on the growth of Syntrophomonadaceae, which perform DIET with methanogens (Methanosaeta and Methanosarcina) for the syntrophic degradation of VFAs.

中文翻译：

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活性炭和针铁矿对挥发性脂肪酸甲烷化反应的比较促进作用。

为了深入了解通过碳基材料和三氧化二铁进行的种间电子转移（DIET），三种导电材料（即活性炭（AC），铁改性活性炭（FEAC）和针铁矿（FEOOH））对甲烷生成的影响从挥发性脂肪酸（VFAs）中进行了评估。在酸胁迫下（〜4 g / L VFA），在FEOOH补充反应器中发现最大甲烷产量为266 mL / g化学需氧量（COD），比AC反应器高48％。FEOOH增强电子传输链活性和细胞外电子转移能力的原因包括：1）对参与产甲烷和产酸作用的含铁酶的激活；2）对功能微生物的选择性富集。